Myostatin and insulin-like growth factors in uremic sarcopenia: the yin and yang in muscle mass regulation.

Myostatin and the insulin-like growth factors (IGF-I and -II) play inhibitory and stimulatory roles, respectively, in the development and regulation of skeletal muscle mass. The findings of Sun et al. in this issue shed light on the potential regulation and actions of this yin-and-yang system in uremic sarcopenia and the salutary effects of exercise.